import java.util.HashSet;
import java.util.Set;

public class TestHashSet {
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		Set<String> s = new HashSet<String>();
		s.add("Naveen");
		s.add(new String("Naveen"));
		s.add(null);
		s.add(null);
		System.out.println(s.size());
	}
}
